In recent years, center pivot systems have come into wide-spread use as very effective means for irrigating farm land. A center pivot irrigation system consists generally of a single pipeline extending radially from a fixed center pivot point. Irrigation water is introduced into the pipeline at the pivot point and is dispersed through sprinklers spaced along the length of the pipeline. The irrigation pipeline is supported on a series of wheel mounted carriages with associated drive motors. The motion of the carriages causes the irrigation pipeline to revolve about the center pivot point, thus, causing the pipeline to traverse and irrigate a large circular area within a field.
The benefit of center pivot irrigation systems over prior irrigation systems is that large tracts of land can be efficiently irrigated with relatively little equipment and little manual labor. However, a drawback of the system has been that only large and symmetrically-shaped fields may be irrigated. A problem also exists with moving center pivot irrigatin systems from one field to another. Because of the large number of towers and the positioning of the wheels on these towers to accommodate circular motion, it is necessary, generally, to dismantle the system entirely in order to move it from one field to another. Although it would be possible to use a number of small center pivot irrigation systems to water irregularly shaped fields, the expense of maintaining and operating such multiple systems would outweigh the benefits, since the amount of equipment required would greatly exceed the amount of equipment necessary to cover a comparable area of ground in a larger field with a single center pivot irrigation system.
One solution to the problem of irrigating small and irregular fields is to use a single mobile center pivot irrigation system that is sufficiently small to operate within the irregular portions of a field and which may be connected to a number of different water supply points within each field. To be feasible, such a system must be readily transferable from one point to another, and therefore, must be adapted to linear movement as well as circular movement about the center pivot point.
A number of inventions as described below have dealt with this problem; however, none have, to date, provided a satisfactory solution.